Node's Perpetuum Mobile


    1.5.3 • Public • Published


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    Custom overlay-scrollbars with native scrolling mechanism for web applications (if needed).

    There is a React wrapper too — react-gemini-scrollbar.

    Problem Description

    Nowadays, some OS’s provides “overlay-scrollbars” natively. Those scrollbars look nice and work well (mostly mobile browsers and OSX opt-in). The problem came when you have to customize the remaining ‘ugly’ scrollbars out there. e.g: “having a sidebar with a dark background + native-non-floating-scrollbars” ...hum, ugly. Even when this problem can be merely visual, for me is a way of enhancing the user experience.

    • Fallbacks to use the native scrollbars when the OS/browser supports “overlay-scrollbars”.
    • Mimics the scrollbar behaviour when replaced with the custom ones (click, drag...).
    • IE9+ support.
    Solution Proposal

    Check the scrollbar size. If the scrollbar size is zero (which means the scrollbars are already “over the content”) then we do nothing. Otherwise we simply “hide” native scrollbar and show custom in its place.






    npm i gemini-scrollbar --save


    bower install gemini-scrollbar --save



    var GeminiScrollbar = require('gemini-scrollbar')
    var myScrollbar = new GeminiScrollbar({
        element: document.querySelector('.my-scrollbar')


    @import (inline) "<path-to-gemini-scrollbar>/gemini-scrollbar.css";


    @import url(<path-to-gemini-scrollbar>/gemini-scrollbar.css);

    Or, you can add the relevant files in your document.

    <link href="<path-to-gemini-scrollbar>/gemini-scrollbar.css" rel="stylesheet">
    <script src="<path-to-gemini-scrollbar>/index.js"></script> 


    name type default description
    element * HTMLElement null The element to apply scrollbars
    autoshow Boolean false Show scrollbars upon hovering
    createElements Boolean true Create and append the require HTMLElements at runtime.
    forceGemini Boolean false Force Gemini scrollbars even if native overlay-scrollbars are available. Useful for development.
    onResize Function null Hook by which clients can be notified of resize events.
    minThumbSize Number (px) 20 Sets the minimum size of the thumbs.

    * required

    Basic Methods

    name description
    create Bind the events, create the required elements and display the scrollbars.
    update Recalculate the viewbox and scrollbar dimensions.
    destroy Unbind the events and remove the custom scrollbar elements.

    Other Mehods

    name description
    getViewElement Returns the scrollable element


    You can change the styles of the scrollbars using CSS. e.g:

    /* override gemini-scrollbar default styles */
    /* vertical scrollbar track */
    .gm-scrollbar.-vertical {
      background-color: #f0f0f0
    /* horizontal scrollbar track */
    .gm-scrollbar.-horizontal {
      background-color: transparent;
    /* scrollbar thumb */
    .gm-scrollbar .thumb {
      background-color: rebeccapurple;
    .gm-scrollbar .thumb:hover {
      background-color: fuchsia;


    • native overlay-scrollbar: We check the scrollbar size using this approach by David Walsh. If the scrollbar size is zero (which means the scrollbars are “over the content”) then we do nothing but add the gm-prevented class selector to the element, which contains the non-standard -webkit-overflow-scrolling: touch; declaration for web devices to use momentum-based scrolling. No event binding, element creation... nothing, in this case, we leave the OS/browser do its job. Why? you already have nice looking scrollbars for free.

    • ::-webkit-scrollbar: If you plan to use gemini-scrollbar on your application I highly recommend you removing any Webkit scrollbar styles you may have, why? using the -webkit- prefixed pseudo-elements will cause Webkit turning off its built-in scrollbar rendering, interfering with our scrollbar-size-check. You can read a bit more about this issue on this commit.

    • create method: The custom scrollbars will not render until you call the create method on the instance. i.e: myScrollbar.create();

    • required height: To avoid unexpected results, it is recommended that you specify the height property with a value to the element you applying the custom scrollbars (or to its parent).

    • body tag: If you want to apply custom scrollbars to body, make sure to declare a height value either to the :root pseudo-class or to the html element. e.g:

      html {
          height: 100%;
          /* or */
          height: 100vh;
          overflow: hidden;
    • createElements option: The createElements option specify wheater or not gemini-scrollbar should create and append the require HTMLElements at runtime. Its default value is true. Passing this option as false will assume that you to have added the required markup with the specific CSS class selectors on them for it to work. i.e:

      <!-- (createElements: false) example markup -->
      <div class="something-scrollable">
        <div class="gm-scrollbar -vertical">
          <div class="thumb"></div>
        <div class="gm-scrollbar -horizontal">
          <div class="thumb"></div>
        <div class="gm-scroll-view">
          All your content goes here.

    This way you can be sure the library will not touch/change your nodes structure. You can read more about the reason of this option on this commit.



    MIT © Noel Delgado


    npm i gemini-scrollbar

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